1. Field of the Invention
The present invention relates to a semiconductor optical device.
2. Related Background Art
Semiconductor lasers are known (see for example Laid-open Japanese Patent Application No. 2001-24282) wherein an n-GaAs buffer layer, an n-Al0.3Ga0.7As lower cladding layer, an active layer, a p-Al0.3Ga0.7As upper cladding layer and p-GaAs cap layer are successively formed on an n-GaAs substrate. The thickness of the n-Al0.3Ga0.7As lower cladding layer is 1500 nm.